Unlike other window companies, we've always been a leader, not a follower in innovative technology. WeatherGard was the first vinyl window manufacturer to offer a fully welded window lineup, Superspacer Warm Edge Spacer Technology for the glass units and standard Low - E/Argon glass units in all windows. WeatherGard's replacement windows are tested and certified to ensure that they meet the most stringent thermal and structural requirements, and have been certified with the EPA, Energy Star, AAMA and the NFRC.